Production of solvents



July 28, 1942.

J. EI.l HARVEY, JR

PRODUCTION OF SOLVENTS Filed March 14. 1941 @faim glu/UWM Patented July 28, 1942 PRODUCTION OF SOLVENTS Jacquelin E. Harvey, Jr., Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia Application March 14, 1941, Serial No. 333,458

6 Claims.

The present invention relates to the production of valuable liquids from tars and fractions thereof, crude and/or refined.

This application is a continuation in part of my application Sr. No. 352,670, led August 14, 1940, for Production of solvents, copending herewith, as to all matter common to the two applications.

An object of the present invention is the subjection of tars of aromatic content and fractions thereof, crude and/or refined to the action of hydrogen in step-wise manner, whereby to provide refined solvents of lowered corrosivity, increased solvency and boiling points, as hereinafter explained.

A further object of the invention is the production of rened solvents of lowered corrosivity, the characteristics of which are, among other things, dependent upon hydrogen supply.

Another object of the invention is the production of refined solvents of lowered corrosivity from tars of aromatic content and fractions thereof, said tars and fractions thereof characterized by content of oxygenated compounds and sulphur.

Other objects of the present invention will be apparent from the following disclosures.

Suitable starting materials of the present invention include all tars and fractions thereof of aromatic content characterized by content lof oxvgenated compounds and sulphur, as for instance as derived from coal and petroleum and gas or gases of carbon content, as for instance coke oven tar, water gas tar, gas house tar, and tars of aromatic content in general; tars produced by cracking hydrocarbons; tars resulting from the action of hydrogen and hydrocarbons; tars resulting from polymerization; high boiling extracts of carbonaceous substances; high boiling hydrocarbons of aromatic content having olenic and /or naphthenic content.

Especially attractive as starting materials are the tars from high temperature coke ovens which are available in large quantities at low prices. Tar fractions previously subjected to the action of hydrogen are suitable starting materials.

The present invention may be viewed broadly as a process for the production of refined solvents of lowered corrosivity by subjecting the starting material, in step-wise manner, to the controlled action of hydrogen whereby to produce solvents of increased boiling points and enhanced solvency.

The following examples serve to illustrate the general principles upon which the practice of the present invention is based, as well as the process of the present invention.

The invention will be understood from the following description of illustrative steps comprising various methods of securing the objects of the invention, when read in connection with the accompanying drawing wherein the gure is a diagrammatic sketch of an apparatus for carrying out a form of the process of the invention and wherein the nature of the step carried out in each chamber and the contents thereof are indicated by legend.

E'zrample 1.-A sulfur bearing coal tar creosote, characterized by content of oxygenated compounds, coke residue in excess of 1%, specific gravity in the order of 1.06, and substantially 25% residue above 355 C. is subjected to the action of hydrogen at 390 C. and 200 atmospheres pressure whereby to lower sulphur content, thereby lowering corrosivity, at least providing for lowered corrosivity in theiinished material as hereinafter described. The creosote of lowered sulphur content is passed in liquid phase through a high pressure reaction vessel while simultaneously iiowing hydrogen therewith in the presence of a molybdenum oxide catalyst and a material selected from the group consisting of halogens, halides and derivatives thereof including substitution and addition products thereof; temperature 435 C. and 300 atmospheres pressure. The time of contact is one hour and the gas flow 14,000 cubic feet per barrel refined creosote. The beneiiciated creosote upon inspection will be found to have a lowered boiling range, specic gravity and viscosity. Some of the lower fractions of the beneficiated creosote will have a lowered solvency as compared to solvents extant of a comparable boiling range.

The beneciated creosote is stripped to an upper limit of 300 C. and the distillate is passed through a high pressure reactor at 525 C. while contacting a tungsten oxide catalyst. The flow of hydrogen is so controlled as to produce a solvent having, as compared to the intermediate starting material, increased boiling points and increased solvency.

The solvent so produced may be fractionated to provide refined solvents of lowered corrosivity of any boiling range within the limitations of the immediate parent material, as for instance comparable with the following:

Benzol 7S-120 Toluol -150 Hi-ash naphtha s -200 Heavy naphtha 150-290 Plasticizers -360 tent with hydrogen while contacting an oxide catalyst and a material adapted to influence the decomposition of oxygenated compounds contained in the processed material whereby to produce an intermediate product of lowered solvency, specific gravity, boiling range and viscosity; stripping from the beneflciated material a fraction thereof and subjecting at least a portion of the distillate to the controlled action of hydrogen whereby to enhance solvency and increase boiling points thus providing the refined solvent of lowered corrosivity and superior solvency of the present process.

Looked at in one manner, the present process provides a method for treating tars of aromatic content and fractions thereof, with hydrogen in step-wise manner whereby to produce refined solvents of lowered corrosvity, said solvents being characterized by increased solvency and boiling points when compared to the intermediate parent material, as heretofore disclosed. The step-wise action of hydrogen being characterized by providing hydrogen in ow that depolyrnerizes-ring multiples thereby inducing lowered specific gravity, boiling range, and solvency, and

last, by providing hydrogen in flow that increases boiling points and solvency. Y

The aforenamed step-wise action of hydrogen thus provides a method for securing the refined solvents of lowered corrosivity and superior sol-V vency from heavy or high `boiling hydrocarbons of aromatic content, said high boilers characterized by the presence of `ring multiplie-ities of thermal susceptibility.

Example 2.-A sulphur containing coal tar,

specific gravity 1.1641, a coke residue in excess of 5%, and in excess of 35% boiling at 355 C. and `further characterized by content of oxygenated compounds is subjected to the action of hydrogen at 400 C. and 200 atmospheres pressure for such a length cf time as to lower sulphur content. The coal tar of lowered sulphur con,- tent is passed in liquid phase to a high pressure reaction chamber while simultaneously flowing hydrogenV therewith at a pressureof 300 atmospheres and a temperature `of 420 C. Time of contact is one hour and flow of hydrogen 12,000 cubic feet per barrel feed stock. The catalyst is molybdenum oxide and a material 'selected from theY group consisting of halogens, halids` and 'derivatives thereof including substitution andV addition products thereof. The thus treated coal tar is found to have an overall lowered specic gravity, viscosity, coke residue, and oxygen content; and in some of its fractional parts a lowered solvency as compared to solvents, extant of Vcomparable boiling range. The beneciated tar is then stripped to-an upper limit of 360 C. and the low boiling portion thereof subjected to the action of a flow of hydrogen at 525 C. and V250 Vatmospheres pressure with the time of contact and gas flow so controlled as to increase boiling points and solvency.

Example 3.-A high boiling coal tar fraction, initial boiling point of substantially 245 C. and characterized by content of sulphur and oxygenated compounds is subjected to the action of vhydrogen at 430 C. and 300 atmospheres pressure while contacting a catalyst and for such a period of timeV as to reduce sulphur content. Y

Y drogen therethrough at a temperature of 410 C. and 350 atmospheres'pressur'e; catalyst, cobalt oxide and a material adapted to influence the decomposition of oxygenated compounds contained in the starting material. Upon inspection of the beneciated coal tar, it will be found to have lowered specific gravity, viscosity, coke residue, boiling range and oxygen content, and, in some of the fractional parts of the beneficiated material a lowered solvency as compared to solvents extant of comparable boiling range.

The beneflciated material is stripped at 290 C. and the distillate subjected to the action of hydrogen at 450 C. and 200 atmospherespressure and the time so controlled as to increase boiling points and solvency. The time element in the last action of hydrogen may be afractional part of a minute, or more, as for instance several minutes.

The residue incidental to any distillation or stripping step may be recycled or used as an article of commerce of enhanced value, as for instance binders or the like.

The starting material of high carbon content, as for instance high temperature coke oven tar, is Ycharacterized by in its raw state such a percentage of high molecular complexes or polymerized products that theY rened solvents of lowered corrosivity of the present invention are not possible of manufacture directly therefrom, but must be produced in step-wise manner as heretofore explained, whereby among other things, the action of hydrogen depolymerizes or partially depolymerizes said molecular complexes contained in the starting material. Y

The depolymerized or partially depolymerized 'tar or fraction thereof of lowered sulphur and oxygenated compound content is then stripped of a percentage of itsl low ends whereby to provide the intermediate parent material of the refined solvents of lowered corrosivity, saidrefined solvents being characterized by increase of boiling points and solvency. The residue of said stripping may, because of its depolymerized or partially depolymerized condition -serve as recycle material to the end that conversion of the starting material in the percentage remaining nally liquid approaches volume for volume of the starting material into the refined solvents of lowered corrosivity of the present invention.

Inv the conversion of starting materials, partially or approaching unity, into the rened solvents of lowered oorrosivity of the'prese'nt process, temperatures as low as 309 C.. may be employed; pressures as low as 50 Vatmospheres may be used. However, temperatures and pressures of increased range provide better commercial practice, and are desirable; Temperatures are preferred that-cause no substantial coking.

Gas ows are usually held in excess of 2,000 cubic feet per .barrel material treated. In the step-wise application of hydrogen a few trials when using any of the starting materials will determine the desirable gas flow, when coordinated with the selected temperature and pressure conditions to effect depolymerization. The gas flow in this instance is a variable quantity because of the varying ranges of coordinated temperature and pressure that may be selected. When using Yany chosen coordination of temperature and fractions to the action of hydrogen in accord- .Y

ance with the present process for the production of solvents and/or plasticizers that'l the formerly accepted teaching that product increment, depolymerization and/or hydrogen absorption are linear functions of the time, is not followed.

When subjecting a mixture of crude coal tar fractions boiling predominantly above 250 C. or 275 C. to the action of hydrogen, research has disclosed that the newly induced products, depolymerization and/or hydrogen absorption are linear functions of the time. As an example, when the above mixture of crude coal tar fractions is subjected to the action of hydrogen for 2, 5, and 8-hour periods, the newly induced products, depolymerization and/ or hydrogen absorption were linear functions of the time element.

One of the preferred starting materials of the present process is a mixture of refined coal tar fractions boiling predominantly above 355 or 380 C. Such a starting material is conveniently the final residue resulting from evaporating coa-l tar to dryness or substantial dryness and then stripping wood preservative from the distillate. This final residue mass of rened coal tar fractions is an especially suitable refined pitch to be used as starting material of the present process. However, in contradistinction to the mixture of crude coal tar fractions boiling predominantly above 250 or 300 C., when the aforenamed preferred starting material is subjected to the action of hydrogen for production of solvents and/or plasticizers, the newly induced fractions, depolymerization and/or hydrogen absorption are not, as described for the mixture of crude tar fractions, linear functions of the time. A critical period of treatment by or with hydrogen exists, and which if exceeded causes loss of newly induced fractions, polymerization and/or lessened hydrogen absorption on certain fractions of the preferred starting material under treatment.

The critical time element because of the obvious possible variations in the characteristics of the aforenamed refined coal tar pitch cannot .l

be spoken of as an arbitrary figure. It can be stated, however, that if the refined coal tar pitch were to be subjected to the action of hydrogen for such a length of time, which for other crude coal tar fractions would illustrate that the newly induced fractions, depolymerization and/or hydrogen absorption were linear functions of the time element, loss of induced products, polymerization and/or lessening of hydrogen absorption would occur. tar pitch by or with hydrogen, the critical time element is in the order of' about three hours.

In the disclosures made herein and in the appended claims distillate removal of low boiling portions from the beneciated material is considered the equivalent of fractional removal by gas movement, solvent action or the like. The converse also obtains.

A sulfur bearing refined coal tar pitch characterized by content of oxygenated compounds, coke residue in excess of 2% and a specic gravity greater than l, is subjected V4to the action of hydrogen at 385 C. and 200 atmospheres pressure whereby to lower sulfur content, thereby lowering corrosivity, at least providing for lowered corrosivity in the finished material as hereinafter described. The hydrogen aotion while lowering sulfur content is so controlled as to preclude substantial induction of low boiling fractions, as for instance, low boiling solvents When treating the refined coal I.,

whose boiling range is disclosed elsewhere herein. The refined coal tar pitch of lowered sulfur content is passed in liquid phase to a high pressure reaction vessel while simultaneously flowing hydrogen therewith in the presence of an oxide catalyst chosen from the group comprising the sixth and eighth periodic groups, and additional catalytic material selected from the group consisting of halogens, halids and derivatives thereof including substitution and addition products thereof; temperature 430 C. and pressure 300 atmospheres. Time of contact is two hours and the gas flow 15,000 cubic feet per barrel material treated. The beneficiated refined pitch upon inspection will be found to have a lowered boiling range, coke residue, specific gravity and viscosity. Solvents selected from some of the lower boiling fractions of the beneciated material will have a lowered solvency as compared to solvents extant of comparable boiling range.

The beneficiated rened coal tar pitch is stripped to an upper limit of 290 C. and the distillate is passed through a high pressure reactor at 5lO C. The flow of hydrogen is chosen from the range below 7,000 cubic feet per barrel material treated, and is so selected that the material flowing from the reactor will have increased low boiling points and solvency as compared to the intermediate starting material.

The solvent so produced may be fractionated to provide fractional cuts as noted in the foregoing.

The residue resulting from the provision of the intermediate starting material may be recycled if desired for further solvent production. The residue is of a more liquid nature than a comparable out on the starting material indicating that the high boiling ends which may be described as including multiplicity of ring structures has been, at least, either saturated or pariially saturated, thus providing the initial step in the step-wise conversion of substantially the entirety of the refined pitch remaining liquid under process conditions into the refined solvents of lowered corrosivity of the present process.

In the instance of the solvent recovered to an upper limit of 290 C., as above described, the solvent cut may be divided to provide solvents of various boiling ranges as may be dictated by necessity. When providing the. intermediate starting material of the present process, and in the event such provision is made by taking a deep cut on the beneiiciaied refined pitch, the deep cut after further hydrogen action, as heretofore described, may provide high boiling fractions having plasticizing properties.

When subjecting a rened coal tar pitch to the action of hydrogen for the production of solvents in accordance with the present process, the hydrogen action characterized by solvent increment is controllably held at or below the critical time period, and if such is exceeded adverse reaction will occur. As an example, if

the critical time period is exceeded, instead of fractional increment, depolymerization and/or hydrogen absorption being linear functions of the time element, the reverse will obtain. In other words, if the critical time period is exceeded, fractional increment, depolymerization and/0r hydrogen absorption will not be linear functions of the time element, it having been found, among other things, that a period in excess of that which is critical will provide for are of superior quality and are characterized by a preponderance of ring structures.

The starting materials of the present invention are characterized by content of oxygenated compounds. By providing as a catalytic material,

one or more selected from the group consist- Z.

ing of halogens, halids, and derivatives thereof including substitution and addition products thereof, the decomposition of the oxygenated compounds contained in the starting material while under the action of hydrogen, is influenced,

thereby enhancing the step-wise production of the refined solvents of lowered corrosivity and superior solvency of the present invention.

The gas flow in the second hydrogen action is held at that point that increases boiling point and solvency thus providing the refined solvents of lowered corrosivity of the present process. A few trials with any of the intermediate starting materials under chosen coordination of temperature and pressure will readily determine the desirable gas flow. For a given coordination of temperature and pressure the gas ow in the final processing is lower than the gas flow in the preceding instance.

Using some starting materials, a gas flow of l0,000-15,000 cubic feet per barrel feed, or higher, has proven satisfactory for depolymerizng condition and, gas flows in the order of 6,000-8,000 cubic feet per barrel feed, or lower, when increasing solvency and boiling points have proven satisfactory. Y

Viewed broadly, the hydrogen flow in the instance of obtaining depolymerizing conditions may be lower than 10,000 cubic feet per barrel feed stock.

In the hydrogen action that lowers sulphur content, the action of hydrogen may be effected in an autoclave or in a continuous plant, and in the event continuous practice is used, the gas ow is maintained as to assist in sulphur reduction and elimination, the while inducing no substantial percentage of carbon or the like, nor percentages of liquid chain structures that would preclude the provision of refined solvents of lowered corrosivity and superior solvency as stated.

By the term beneciated as used herein and in the appended claims is meant the starting material at least once subjected to the action of hydrogen in accordance with the present process.

After the starting material has been subjected to depolymerizing action, the stripping step may be effected at any point selected within arwide range to provide a cut capable of providing, after further processing, substitutes for the boiling range of benzol, toluol, xyol, naphthas and/or plasticizers.

Thus, the depolymerized starting material may be cut according to the need at hand, said Vcut being then subjected to the action of hydrogen that increases solvency and boiling points.

The catalysts of the present invention are oxides and a material adapted to influence the Vdecomposition of oxygenated compounds contained in the starting material. Oxides of metals of the 6th and 8th periodic groups may be used, however the oxides of the other groups may be employed. Diflicultly reducible oxides are preferred. The catalyst or catalysts may be employed in any form, as for instance pellets, comminuted, supported on carriers, or the like.

If desired, comminuted catalysts may be used in the step characterized by depolymerization, and in the step characterized vby solvency increase, a rigid catalyst may be used.

By the term multiplicity of rings, high molecular complexes, and polymerized products, are meant high boiling fractions of aromatic content, a portion of which may be viewed as ring multiples; or said terms, any or all, may be used to describe the high boiling fractions of the starting material, which because of high carbon content, are especially susceptible to thermal degradation.

When subjecting high boiling fractions of the starting material to the process of the present invention, it may be desirable prior to the depolymerizing step, or the sulphur reduction step, to at least partially depolymerize the molecular complexes by use of a solvent. Said solvent may be added in a small amount, or up to volume for volume may be used.

Concerning solvents, it may be said that tar itself as for instance high temperature coke oven tar, isfconstituted of high molecular complexes dissolved, cut back or depolymerized with a solvent, said solvent being the lower lboiling frac,- tions of said tar.

The action of hydrogen as aforestated may be effected in one or more cycles carried out in chambers, with or without releasing the pressure and with or without variation of process controls, including changes in either temperature, pressure and/or gas flow.

Various modes of practicing the present invention are possible; for instance the depolymerized starting materials may be stripped as for instance by gas movement; the low ends thus stripped may then, with or without releasing pressure, be subjected to the action of hydrogen that increases solvency and boiling points. desired stripped material may be obtained by partial release of pressure which would correspond to the fractional recovery desired or predetermined.

The process may be practiced in an autoclave and/or a single high pressure reaction chamber, a series thereof, a parallelism thereof, including a multiplicity thereof.

The refined solvent of the present invention characterized by lowered corrosivity and superior solvency may, as aforestated, be fractionated to provide solvents and/or plasticizers of various boiling ranges, and in the instance where sol-` vents are processed from a deep cut on the depolymerized material, the highest boiling fraction thereof may serve as a substitute for certainV plasticizers.

In the rst cycle of hydrogen action that re-V sure release is considered the equivalent of dis-V tillation.

Or the When reference is made to high molecular 60mplexes contained in the starting material, and when the starting material contains low boiling fractions that are not considered high molecular complexes, it is of course obvious that the high molecular complexes contained in the starting material are to a certain extent depolymerized by the solvent present.

It will be seen that by reduction of sulphur content of the material under treatment during any stage of hydrogen action, the oxide catalyst used during subsequent stages is at least partially protected from the effect of the sulphur.

The decomposition influencer which it is desired to have present in the reaction zone is generally taken between 0.1 and 4 or 5 percent, based on the feed stock, and is preferably taken between 0.1 and 1.5 percent.

Halogens, halids and derivatives thereof are employed for catalytic purposes noted in the foregoing; however, also may be employed substances furnishing under the process conditions a halogen or a hydrogen halid. Ammonium chloride may be employed, also halogen compounds of coal tar oils or the like, as for instance the iodides or bromides. Also may be employed acids, such as nitric, sulphuric, sulphonic, formic and acetic.

The addition of the decomposition influencer may be made prior to the entry of the feed stock into the reaction chamber, or at any suitable time, as for instance after the charging stock has been heated.

Equivalent amounts of compounds furnishing halogen or hydrogen halid may be employed.

The evaluation of solvent power is conveniently accomplished by finding the well-known aniline point or kauri-butanol number. The evaluation of plasticizing properties is conveniently accomplished by recourse to methods suggested in chapter VI, The technology of solvents by Dr. Otto Jordon, Mannheim, Germany, translated by Alen D. Whitehead, Chemical Publishing Company of New York, Incorporated, New York, New York.

Minor changes may be made without departing from the spirit of the invention.

I claim:

1. In the production of a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen at a temperature and pressure of at least 300 C. and 50 atmospheres, respectively, and for such a time as to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high flow of hydrogen in the presence of an oxide catalyst and a material selected from the group consisting of halogens, halids and derivatives thereof for a period not in excess of about three hours at a temperature and pressure in excess of 300 C. and 50 atmospheres, respectively, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneficiated material; and increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 2000- 8000 cubic feet per barrel material treated at a pressure of at least 50 atmospheres and a temperature of 45o-525 C., to produce a solvent.

2. In the production of a solvent from a sulphur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen whereby to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high flow of hydrogen in the presence of an oxide catalyst and a material selected from the group consisting of halogens, halids and derivatives thereof for a period not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneficiated material; increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 2000-8000 cubic feet per barrel material treated; and fractionating the last named beneciated material to segregate a solvent.

3. In the production of a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly about 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen whereby to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high flow of hydrogen in the presence of an oxide catalyst and a material selected from the group consisting of halogens, halids and derivatives thereof for a period of not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneciated material; increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen within the limits of about 2000-8000 cubic feet per barrel material treated; and fractionating the last named benelciated material to provide a solvent boiling preponderantly between and 150 C.

4. In the production of a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a Wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of hydrogen whereby to lower sulfur content, whilst precluding substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relatively high ow of hydrogen in the presence of a catalyst selected from the group consisting of halogens, halids and derivatives thereof for a period of not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneciated material; and increasing the boiling points of at least a.

chosen portion of said stripped fractions by-subjecting'samewto theaction-of a relatively low flow of hydrogen not in excess of about 8000 cubic feet per barrelfeed stock, to produce a solvent.

5. VIn the production of -a solvent from the sulfur containing refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a -liquid useful as a Wood preservative, and a'higher boiling fraction boiling predominantly about 355 C., the process which comprises: subjecting said higher boiling fraction to the action of Vhydrogen at a temperatu-re and pressure of -at least 300 C. and 50 atmospheres, respectively, and for such a time as to lower sulfur content, Whilst precluding .substantial lovv boiling fractional increment; subjecting the material of lowered sulfur content lto the action of a relatively'high flow of hydrogen in the presence of an oxide catalyst and a -ma-terial selected from the group consisting of halogens, halids and derivatives thereof at a pressure inexcess of about 50 atmospheres, a temperature in 'excess of about 300 C. and for a period not in excess of about three hours, whereby to L avoid polymerization;` stripping newly induced fractions rfrom the beneciated material; and increasing the boiling points of at least a chosen portion cf said stripped fractions by subjecting same to the action of a relatively low iicw of hydrogen Within the limits of about 200G-8000 cubic feet per barrel material treated at a pressure of at least 'about -50 atmospheres `and a tem'-l perature of 450-525 C., to produce a solvent.

6.In the produc-tion of a solvent from the sulfur containing refined pitch produced by stripping -high temperature coal tar to 'at least about substantial dryness, and `fraction-ating tl'ie overhead material to recovera-liquid useful asa wood preservative, and a higher boilingrfraction boiling predominantly above 355 C., the vprocess Which comprises: subjecting said higher boiling fraction to the action of hydrogen whereby to lower sulfur content, whilst rpreclud-ing substantial low boiling fractional increment; subjecting the material of lowered sulfur content to the action of a relativelyA high flow of hydrogen in the presence of an oxide lcatalyst and a material selected from the group consisting of halogen's, halids and derivatives thereof at a temperature and pressure in excess of about 300 C. and about 5'()l atmospheres, respectively, yfor va period rnot in excess of about three hours, whereby to avoid lowered hydrogen absorption; stripping newly inducedfra'ctions from the beneiciateoll material; and increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low 4iioW of hydrogen Within the limits of about 3000-8000 cubic feet per barrel material treated, to yproduce a solvent.

JACQUELIN E. HARVEY, JR. 

